**Irina**** YEHORCHENKO**

Institute of Mathematics

3 Tereshchenkivs'ka Street

01601
Kyiv-4

**Phone:**

+380
(44) 234 63 22 (office)

**Fax:**

+380 (44)
235 2010 (office)

**E-mail:** iyegorch@imath.kiev.ua

*Ph.D.
in Math.*: 1989, Institute of Mathematics, Kyiv (Supervisor Prof. W.I. Fushchych)

*M.Sc**. in Math.*: 1984,

**Professional Experience:**

Research
Fellow at the Department of
Applied Research of the

**AREA**** OF EXPERTISE:**

**Other activities:**

Member of the Organising
Committee of the conferences ``Symmetry in Nonlinear
Mathematical Physics''

(Kyiv, Ukraine, 1995, 1997, 1999, 2001, 2003,
2005, 2007, 2009)

Associate
Editor, SIGMA

Member of
the Organising Committee of the Voronoi
Conferences (Kyiv, Ukraine, 1993, 1998, 2003, 2008)

Reviewer, Mathematical Reviews

1.
**Yehorchenko**** I.A. **Reduction of Multidimensional Wave Equations to
Two-Dimensional Equations: Investigation of Possible Reduced Equations, Proceedings of the 5th Workshop
"Group Analysis of Differential Equations & Integrable Systems", Protaras, Cyprus, 2011, p. 225-235, arXiv:1010.4977

2.
**Yehorchenko**** I.A. **Differential Invariants and Hidden Symmetry, arXiv:1010.5313

3.
**Yehorchenko**** I.A. **Conditional Symmetry and Reductions for the
Two-Dimensional Nonlinear Wave Equation. I. General Case, arXiv:1010.4913

4.
**Yehorchenko**** I.A. **Reduction of non-linear d'Alembert equations to
two-dimensional equations, Proceedings
of the 4th Workshop "Group Analysis of Differential Equations &
Integrable Systems", Protaras, Cyprus, 2009, p. 243-253, arXiv:0910.2501

5.
**Yehorchenko**** I.A., **Vorobyova A.I. Infinite-dimensional symmetry for wave equation
with additional condition, arXiv:0910.2380

6.
**Yehorchenko**** I.A. **Differential Invariants of Infinite-Dimensional
Algebras That Are Equivalence Algebras of Classes of

7.
**Yehorchenko**** I.A. **General Results on Conditional Symmetry for the
Two-Dimensional Nonlinear Wave Equation, arXiv:0910.1946

8.
**Yehorchenko**** I.A. **Relative invariants for Lie algebras: construction
and applications, Symmetry and Perturbation Theory, Proceedings of the
International Conference on SPT 2007. Otranto, Italy, 2 - 9 June 2007, G.
Gaeta, R. Vitolo and S. Walcher (Eds.), World Scientific (2007), p. 282-284

9.
**Yehorchenko**** I.A. **Reduction of multidimensional non-linear
d'Alembert equations to two-dimensional equations: ansatzes, compatibility of
reduction conditions, Collection
of Papers Dedicated to 70th Anniversary of W.I. Fushchych, Kyiv,

10. **Yehorchenko**** I.A. **Differential invariants for
infinite-dimensional algebras, in *Proceedings**
of the International Conference on SPT 2004*, Cala
Gonone, Sardinia, Italy, May 30 – June 6, 2004;
Editors G. Gaeta, B. Prinari,
S. Rauch-Wojciechowski and S. Terracini,
World Scientific, 2005, p. 308-312 [pdf] (see math-ph/0607002).

11. **Yehorchenko**** I.A. **Group classification with respect to hidden
symmetry, in *Proceedings of Fifth International Conference ``Symmetry in
Nonlinear Mathematical Physics''* (June 23-29, 2003, Kyiv), Editors A.G. Nikitin, V.M. Boyko, R.O. Popovych and I.A. Yehorchenko,
Kyiv, Institute of Mathematics, 2004, V.50, Part 1, 290-297 [pdf].

12. **Yehorchenko**** I.A.**, Vorobyova A.I. Sets
of conditional symmetry operators and exact solutions for wave and generalised heat equations., in *Proceedings of Fifth
International Conference ``Symmetry in Nonlinear Mathematical Physics'' *(June
23-29, 2003, Kyiv), Editors A.G. Nikitin, V.M. Boyko, R.O. Popovych and I.A. Yehorchenko, Kyiv, Institute of Mathematics, 2004, V.50,
Part 1, 298-303 [pdf].

13. **Yehorchenko**** I.A.** Differential invariants and construction of conditionally
invariant equations, *Symmetry in nonlinear mathematical physics, Part 1,
Proceedings of Inst. Mathematics of National Acad. Science of Ukraine (*Kyiv,
2001*)*, 2002, V. 43, 256-262 [pdf] (see math-ph/0304029).

14. Popovych R.O., **Yehorchenko****
I.A.** Group classification of generalized eikonal
equations, *Ukrainian Math. Journal*, 2001, V. 53, N 11, 1513-1520 (in
Ukrainian); translation in Ukrainian Math. J., 2001, V. 53, N 11, 1841-1850
(see math-ph/0112055).

15. Vasilenko O.F., **Yehorchenko****
I.A.** Group classification of multidimensional nonlinear wave equations, *Group
and analytic methods in mathematical physics, Proceedings of Inst. Mathematics
of National Acad. Science of Ukraine, *Kyiv, 2001, V. 36, 63-66 (in
Ukrainian) [pdf].

**Yehorchenko**** I.A.** On symmetry of a class of first order PDEs, *Symmetry in nonlinear mathematical physics, Part
1, 2, Proceedings of Inst. Mathematics of National Acad. Science of Ukraine (*Kyiv,
1999*)*, 2000, V. 30, 245-248 [pdf].

17. **Yehorchenko**** I.A.** Ansatzes and exact
solutions for nonlinear Schrödinger and wave equations, *Symmetry and
analytic methods in mathematical physics (in Ukrainian), Inst. Mathematics of
National Acad. Science of **Ukraine**, *Kyiv, 1998, V. 19, 80-87 [pdf

18. **Yehorchenko**** I.A.** Differential invariants for a nonlinear
representation of the Poincaré algebra. Invariant
equations, *Symmetry in nonlinear mathematical physics, Vol. 1, 2, National
Acad. Science of **Ukraine** (Kyiv), *1997, 200-205 [pdf

19. **Yehorchenko**** I.A. **New
nonlinear Poincare-invariant equations, Proceedings
of the XXI Colloquim "Group Theory the Physics",
Goslar, Germany, 1996, World
Scientific, 1997, p. 1022-1026

20. **Yehorchenko**** I.A.** Second-order differential invariants for some
extensions of the Poincaré group and invariant
equations, *J. Nonlin. Math. Phys.*, 1996, V. 3,
no. 1-2, 186-195 [pdf].

21. Fushchych W.I. and **Yehorchenko****
I.A.** New conditionally invariant solutions for non-linear d'Alembert equation, Preprint LiTH–

**Yehorchenko**** I.A.** Second-order differential invariants for the Poincaré, Galilei and conformal
algebras in many-dimensional spaces, *Classical and quantum systems *(* *World Sci. Publishing, River Edge, NJ, 1993, 738-741.

23. **Yehorchenko**** I.A.** Nonlinear representation of the Poincaré algebra and invariant equations, S*ymmetry
analysis of equations of mathematical physics, *Nat. Acad. Sci. Ukraine, Inst. Math., Kyiv, 1992, 62-65.

24. Fushchych W.I. and **Yehorchenko****
I.A.** Second-order differential invariants of the rotation group O(n) and of its extensions: E(n); P(1,n); G(1,n), *Acta** Appl. Math.*,
1992, V. 28, N 1, 69-92 [pdf].

25. **Yehorchenko**** I.A.**, Vorobyova A.I.
Conditional invariance and exact solutions of the Klein-Gordon-Fock equation, *Reports of Acad. Science of Ukraine*,
1992, N 1, 19-22, 176 (in Ukrainian).

26. **Yehorchenko**** I.A.**, Vorobyova A.I.
Conditional invariance and exact solutions of a nonlinear heat equation, *Reports
of Acad. Science of Ukraine*, 1992, N 3, 20-22, 160 (in Ukrainian).

27. Fushchych W.I. and **Yehorchenko****
I.A.** Non-Lie ansätze and conditional symmetry of
the nonlinear Schrödinger equation, *Ukrainian Math. Journal*, 1991, V.
43, N 12, 1620-1628 (in Ukrainian); translation in Ukrainian Math. J., 1991, V.
43, N. 12, 1507-1515 [pdf].

28. Fushchych W.I., **Yehorchenko****
I.A.** On the reduction of the nonlinear multi-dimensional wave equations and
compatibility of the d'Alembert-Hamilton system, *J.
Math. Anal. Appl.*, 1991, V. 161, N 2, 352-360 [pdf].

29. Fushchych W.I., **Yehorchenko****
I.A.** Reduction and solutions of a nonlinear equation for the vector
potential, *Reports of Acad. Science of Ukr. SSR,
Ser. A*, 1991, N 4, 23-25, 158 (in Ukrainian) [pdf].

30. **Yehorchenko**** I.A.** Exact solution of the non-linear d'Alembert equation. In the book: Symmetries and Algebraic Structures in Physics, Proceedings of the XVIII International
Colloquium on Group Theoretical Methods in Physics, Moscow, USSR, June 4-9,
1990, Vol. 2, V.V. Dodonov. and V. Man'ko Eds, Nova

31. Fushchych V.I., **Yehorchenko****
I.A.** Reduction of a multidimensional nonlinear wave equation to
two-dimensional equations, *Reports of Acad. Science of Ukr.
SSR, Ser. A*, 1990, N 8, 32-34, 86 (in Ukrainian) [pdf] (see math-ph/0610020).

32. **Yehorchenko**** I.A.** Differential invariants of Euclidean algebra, *Ukrainian
Math. Journal*, 1990, V. 42, N 6, 767-772 (in Ukrainian); translation in
Ukrainian Math. J., 1990, V. 42, no. 6, 676-681.

33. **Yehorchenko**** I.A.** Stationary solutions of the nonlinear wave
equation, *Algebra-theoretic analysis of equations in mathematical physics,
Acad. of Science of Ukr. SSR, **Institute** of **Mathematics**, Kyiv*, 1990, 26-30 (in Russian).

34. **Yehorchenko**** I.A.** Exact solutions of the nonlinear Schrödinger
equation, *Symmetry and solutions of equations of mathematical physics*,
Acad. of Science of Ukr. SSR, Inst. Mathematics,
Kyiv, 1989, 17-20 (in Russian).

35. **Yehorchenko**** I.A.** Symmetry properties of nonlinear equations for
a complex vector field, Acad. Science of Ukr. SSR,
Kyiv, Inst. Mat. Preprint N 89.48, 1989, 39 p. (in Russian).

36. Fushchych W.I. and **Yehorchenko****
I.A.** Differential invariants of the Poincaré
algebra and of the conformal algebra, *Reports of Acad. Science of Ukr. SSR, Ser. A*, 1989, N 5, 21-22 (in Ukrainian) [pdf].

37. Fushchych W.I. and **Yehorchenko****
I.A.** Differential invariants of the Galilei
algebra, *Reports of Acad. Science of Ukr. SSR,
Ser. A*, 1989, N 4, 29-32, 86 (in Ukrainian) [pdf].

38. Fushchych W.I. and **Yehorchenko****
I.A.** The symmetry and exact solutions of the nonlinear d'Alembert
equation for complex fields, *J. Phys. A*, 1989, V. 22, N 14, 2643-2652 [pdf].

39. **Yehorchenko**** I.A.**, Vorobyova A.I.
Exact solutions of the wave equation with additional conditions, *Symmetry
and solutions of equations of mathematical physics, *Acad. of Science of Ukr. SSR, Inst. Mathematics, Kyiv, 1989, 21-25 (in Russian).

40. **Yehorchenko**** I.A.** Complex generalization of the Hamilton-Jacobi equation and its solutions, *Symmetry analysis and
solutions of equations of mathematical physics, *Acad. of Science of Ukr. SSR, Inst. Mathematics, Kyiv, 1988, 4-8 (in Russian).

41. Fushchych W.I., **Yehorchenko****
I.A.** Symmetric properties of complex-valued nonlinear wave equations, *Reports
of Acad. Science of USSR*, 1988, V. 298, N 2, 347-351 (in Russian) [pdf]; translation in Soviet Phys. Report, 33 (1988), N
1, 36-38.

42. **Yehorchenko**** I.A.** Particular solutions of two systems of
nonlinear multidimensional wave equations, *Symmetry and solutions of
nonlinear equations of mathematical physics, *Acad. of Science of Ukr. SSR, Inst. Mathematics, Kyiv, 1987, 47-54 (in Russian).

43. **Yehorchenko**** I.A.** Poincaré-invariant quasilinear wave equations for complex-valued functions,
Acad. Science of Ukr. SSR, Kyiv, Inst. Mat., Preprint
N 87.3, 1987, 27 p. (in Russian).

44. **Yehorchenko**** I.A.** On the group classification of equations for a
complex vector potential, *Group-theoretic investigations of the equations of
mathematical physics*, Acad. of Science of Ukr.
SSR, Inst. Mathematics, Kyiv, 1985, 66-70 (in Russian).